Solid-fueled cooking or heating device

ABSTRACT

A solid-fueled cooking or heating device that stays relatively cool on the sides and bottom of the device during continuous operation. The inventive device utilizes the flow of inlet combustion air in conjunction with three parallel air spaces to heat the inlet air and cool the exterior of the device. The inventive device has uses ranging from a portable camp stove to a fondue pot burner to a patio heater.

BACKGROUND

1. Field of the Invention

This invention relates generally to combustion technology and, more specifically, to solid-fuel burning stoves generally of a portable nature.

2. State of the Art

Combustion in a fireplace or in a wood stove is used within the home and also outdoors to provide warmth, cooking heat, a source of relaxation, and ambiance. Common situations range from a romantic evening around a fireplace, to a barbecue in the park, to a campfire in the mountains. However, combustion can be dangerous. The unknowing toddler or the unaware adult may come in contact with a hot stove and be injured.

Additionally, many stoves, especially portable ones, run on liquid or gaseous fuels. Liquid- or gaseous-fueled fires are often easy to start and maintain. There is also often very little smoke produced or ash residue left behind. Additionally the flame temperature is generally higher for liquid or gaseous fuels than for solid fuels. However, there are numerous situations where it would be desirable to run on solid fuel. For example, when a person desires the aroma of wood in either a room or in a camping setting. In emergencies, liquid or gaseous fuel may not be available and whatever is available, such as pinecones, twigs, branches, etc., must be used. Additionally, if a solid-fuel fire has the proper airflow more complete combustion will result in less smoke and ash residue.

Additionally, solid fuel has different air-flow considerations than when using a liquid or gaseous fuel burner. For example, if a solid fuel such as split wood logs is just set in an enclosed container such as an open barrel and ignited, the likely result is a fire that smokes a lot and is difficult to maintain. If ventilation is unencumbered, as a solid fuel burns, hot gases will travel rapidly upwards. The natural tendency is for fresh air to be pulled in towards the bottom of the combustion, if there is an unencumbered path for fresh, cooler, air to do so. This is because hot gas is less dense than cold air and so gravity results in the hot air rising and fresh air being sucked into the bottom of a fire. Without gravity, fresh oxygen is not “sucked” into the bottom of the fire. For example, a match burning on the space shuttle does not have a candle shape, but has a spherical shape. The match will not burn long because it is difficult for new oxygen to enter the fire and for the combustion gases to leave. Without the aid of gravity the gases are only moved by diffusion.

Although wood burning in a barrel, for example, does have the benefit of gravity, the fresh oxygen has to compete for the same air space as the rising exhaust gas. Additionally, partially burned wood and ash from the top layer of the burning wood can clog the lower layers of wood and further impede combustion of the remaining wood. What is needed is a stove that works with the nature of solid-fuel combustion to provide the necessary air flow to more than just the top layer of the fuel and in a manner that air space competition between the fresh air and exhaust gases is reduced.

U.S. Pat. No. 5,024,208 (hereinafter the '208 Patent) discloses a portable solid fuel stove that has fiber insulation in a binder around a circular sheet metal sidewall, and partial cooling chambers in the bottom of the stove. U.S. Pat. No. 3,279,452 (hereinafter “the '452 Patent”) discloses a stove that utilizes two airway passages to preheat the inlet combustion air.

Additionally, the devices of the '208 and '452 Patents only provide air to the bottom of the solid fuel. That is sufficient for fuel that has already been partially burned like charcoal. However, solid fuels such as wood or coal give off combustible gases, called volatiles, when first heated. If insufficient fresh air is provided at the top of the solid fuel these gases may not be burned, the energy released, and the gases converted to carbon dioxide and water. Therefore, these combustible gases would be undesirably ejected into the environment.

It would be advantageous to have a stove that is capable of use in a variety of settings and a variety of applications and that is, at the most, only warm to the touch on the sides and bottom of the device, even when in full and continuous operation. It would also be advantageous to use the inlet combustion air to cool the sides and bottom of the stove rather than solid insulation. It would be advantageous to have a solid-fueled stove that provided for complete combustion of a wide variety of solid fuels.

SUMMARY OF THE INVENTION

The present invention includes solid-fueled cooking or heating devices, especially portable ones, which stay relatively cool on the sides and bottom of the device during continuous operation. In one illustrative embodiment, such devices utilize the flow of inlet combustion air in conjunction with three parallel air spaces to heat the inlet air and cool the exterior of the device. Such devices have uses ranging from a portable camp stove to a fondue pot burner to a patio heater.

In one illustrative embodiment, a device in accordance with the principles of the present invention may be a heating apparatus which includes a heating chamber with at least one air intake in the side of the chamber, a safety structure formed from an inner shell, an intermediate shell, and an outer shell, The heating chamber and the safety structure may be operably connected such that three parallel air spaces exist between the heating chamber and the exterior of the outer shell, and air can flow from an at least one air intake in the outer shell to at least one air intake in the heating chamber via the three air spaces.

In another illustrative embodiment, the inventive device may be a stove that includes a removable bucket operatively connected to an insulative ductwork having at least three concentric chambers. The present invention further includes methods of generating heat, by combusting solid fuel in a removable container; providing at least a portion of the combustion air to the removable container through a side of the removable container, where the at least a portion of the combustion air is traveling through at least one pre-heating jacket encircling the removable container, prior to entering the container.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, which illustrate a cylindrical embodiment of the invention:

FIG. 1 is a perspective drawing of one embodiment of the invention;

FIG. 2 is a cutaway perspective drawing of the preferred embodiment shown in FIG. 1 along the line 1-1;

FIGS. 3A-8C are detailed drawings of components of the embodiment of the stove shown in FIGS. 1 and 2;

FIG. 3A is an elevational view of a fire bucket with a bail;

FIG. 3A-1 is an enlarged view of the area within circle 3-3 of FIG. 3A;

FIG. 3B is an elevational view of a fire bucket without a bail; and

FIG. 3C is a plan view of a fire bucket;

FIG. 4A is a sectional view of the outside shell;

FIG. 4B is a plan view of the outside shell;

FIG. 4C is an elevational view of the outside shell;

FIG. 4D is an elevational view of the outside shell of FIG. 4C unrolled;

FIG. 5A is a perspective view of a section of an intermediate shell;

FIG. 5B is a plan view of an intermediate shell;

FIG. 5C is an elevational view of an intermediate shell;

FIG. 5D is an elevational view of an intermediate shell laid out;

FIG. 6A is a perspective view of a section of an inner shell;

FIG. 6B is a plan view of an inner shell;

FIG. 6C is an elevational view of an inner shell;

FIG. 6D is a sheet metal layout of the elevational view of FIG. 6C;

FIG. 7A is a perspective view of a bottom lid that can be attached to either of FIGS. 4A, 5A, and/or 6A;

FIG. 7B is an elevational view of the bottom lid of FIG. 7A;

FIG. 7C is a plan view of the bottom lid of FIG. 7A;

FIG. 8A is a perspective view of a top lid;

FIG. 8B is an elevational view of the top lid shown in FIG. 8A;

FIG. 8C is a plan view of the top lid shown in FIG. 8A.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 through 8C provide an illustration of a cylindrical embodiment of the stove. However, it should be abundantly clear that numerous variations to the geometries shown in FIGS. 1 through 8C can be made. FIG. 1 shows a perspective view of a cylindrical embodiment of the stove. FIG. 2 is a cutaway perspective of the embodiment shown in FIG. 1 along the line 1-1.

FIG. 2 illustrates a stove 10 comprised of a fire bucket 20, an outer shell 40, an intermediate shell 50, and an inner shell 60.

Referring now to FIG. 3A, this is a further illustration of the fire bucket 20 shown in FIG. 2. Fire bucket 20 consists of a side 30, and a bottom 38. The fire bucket 20 may include a bail 37 as shown in FIG. 3A or without a bail 37 as shown in FIG. 3B. Bracket 36 shown in FIG. 3A and shown in an expanded view in FIG. 3A-1 can be used to attach the bail 37 to the fire bucket 20. However, the bail 37 could also be attached through a hole in the side 20. There are numerous potential variations of the bail 37, such as a wire rod handle attached to the inside of the lip of the fire bucket 20. The bail 37, for example, could be 4 inches to 6 inches long.

Additionally, the fire bucket 20 may be designed with a rolled lip so that it may rest on top of the lid 80. However, the fire bucket 20 may also be designed so that it does not rest upon the lid 80. Furthermore, the fire bucket 20 is removable. This facilitates the dumping of ashes. Additionally, even when the fire bucket 20 is in use it can be removed from the stove 10 and carried to a water source to extinguish the fire. This provides an advantage over the traditional campfire where water or dirt has to be carried to the fire.

Additionally, the fire bucket 20 may also double as a decorative log basket for storing wood and other solid fuels. The fire bucket 20 as a log basket could be designed to stand alone on the floor or to rest on a stand. This embodiment would have the aesthetic benefits of a log basket and the convenience of being able to set the fire bucket 20 directly into the stove. This is unlike a traditionally fireplace or stove that requires the additional step of unloading the log basket and placing the wood in the fireplace or stove. Some of the geometries common to log baskets that could be applied to the fire bucket 20 are saddle shapes, cuboids, and the half-pie of a cylindrical section.

FIG. 3C is a top plan view of the fire bucket 20 shown in FIG. 2 and shows the difference between the bottom radius and the top radius of that embodiment of fire bucket 20. However, a straight cylindrical embodiment could be used as well. All that is necessary is that the overall design be such that air can travel between the inner shell 60 and the side 30 of the fire bucket 20. Therefore, the one or more air intakes 32 may be in the bottom 38 of the fire bucket 20. Also, it may be beneficial to have a different geometry for the fire bucket 20 than for the inner shell 60.

For example, the sloped side 30 shown in FIGS. 3A, 3B, and 3C and the inner shell 60 create an air space 26. As shown in FIG. 2, air space 26 narrows towards the top lid 80 as the sloped side 30 comes together with the inner shell 60. The narrowing of the air space 26 captures volatiles that have diffused out of the fire bucket 20 through the air intakes 32. The capturing structure allows the volatiles to mix with oxygen and before being drawn back into the fire bucket 20. The sloped side 30 also facilitates the exterior cooling/heat exchange that takes place during the operation of the stove 10. Hot exhaust and other gases trapped in the tapered portion of air space 26 are drawn downward into the air intakes 32 in the side 30 and/or the bottom 38.

The amount of energy radiated from a hot surface depends somewhat upon the nature of the surface. Therefore, it may be desirable for the inner side of inner shell 60 and the inside of side 30 and bottom 38 of the fire bucket 20 to be either made of a highly reflective material. Alternatively, a reflective liner could be used instead. A highly reflective surface would mean that less of the energy is absorbed by the fire bucket 20 and inner shell 60, and therefore less heat would be transferred towards outer shell 40. Additionally, it may be desirable to have the outside of side 30 and bottom 38 to be lined with or constructed of material that is unreflective to more readily absorb the radiation reflected back from the inside of inner shell 60. That would result in less of the energy being transferred by radiation from the fire bucket 20 to the inner shell 60 and to the intermediate shell 50 and so on. The liner could also be a spray-on coating such as a reflective or dull paint. Of course, if different materials are used one must take into account the different rates of thermal expansion of the different materials to ensure compatibility or to properly design the stove to compensate for the differing rates of thermal expansion.

The embodiment shown in FIG. 3C shows multiple air intakes 32 in the side 30 of the fire bucket 20, and in the bottom 38. For example, in the embodiment shown in FIG. 3C it is desirable to have approximately 20% to 25% of air intakes 32 in the bottom 38. The at least one air intakes 32 allow for super heated volatiles that have entered air space 26 (see FIG. 2) to mix with fresh oxygen before being drawn by convection back in through the air intakes 32 and into the fire bucket 20. However, it is not necessary that the air intakes 32 be in both the side 30 and in the bottom 38. For example, in a fire bucket 20 with a 4 inch or 6 inch top radius, it may be desirable to have between 9 and 12 air intakes 32 in the bottom 38. The air intakes 32 need only be placed such as to provide or direct airflow along nearly the entire surface of the inner shell.

FIGS. 4A through 4D illustrate an embodiment of the outer shell 40 of the stove 10. Outer shell 40 may be embodied as a cylinder that could be constructed from a single piece of sheet metal as shown in FIG. 4D. A bottom 48 is attached to the bottom of the outer shell 40. One or more air intakes 42 and access 44 are openings in the outer shell 40, as shown in FIGS. 4C and 4D. Access 44 is an opening in outer shell 40 to allow access to a fan 49 if a fan 49 is present. However, if a fan 49 is not present it may not be desirable to have an access 44. Fan 49 may be any number of air blowing devices. For example, fan 49 could be a fan mounted to an electric motor that is contained with the stove 10. Another example of fan 49 is where a pulley driven fan is driven by an exterior motor, hand crank, or foot crank. Fan 49 could also be any source of compressed air, such as a bicycle tire pump, weed sprayer, or air compressor. Where an electric motor is used the motor could run on either AC or DC power. Although not shown, a battery or electrical connection could be provided to supply power to the electric motor.

FIG. 4A illustrates a bottom 48 attached to the outer shell 40. Where stove 10 may be used on patios, decks, etc., this provides a relatively cool bottom surface. This can provide protection against the accidental ignition of materials underneath the stove 10.

FIG. 4C illustrates a damper 46 in phantom. The damper 46 may be moved up or down by a knob 45. Although the knob 45 is shown as a knob. Knob 45 could also consist of a lever, button, or any other device useful for changing the position of the damper 46. The knob 45 may be threaded so that the knob 45 is loosened to move the damper 46, and then retightened to hold the damper 46 in place. That embodiment would require a track be opened in the outer shell 40 to allow for the movement of knob 45. Alternatively, the knob 45 could be permanently fixed to the damper 46, and a track in the outer shell 40 could be designed in a comb shape such that there were rest positions for the knob 45 to place the damper at %/, V₂, and 3/4 open. In addition, damper 46 may be electrically controlled as well.

There may be multiple dampers 46 with an accompanying multiple knobs 45. For example, each air intake 42 could have an individual damper 46. Access 44 could also have its own damper 46 that would also serve as a door for access to the fan 49. Furthermore, the damper 46 may be rotated in from the side, slid down from above as shown in FIG. 4C, or lifted up as a flap. Damper 46 may be on the interior or the exterior of outer shell 40. The damper 46 could even be built into the inner shell 60, the intermediate shell 50, or even as an exhaust damper if desired. Any means capable of retarding air intake or exhaust release may serve as a damper 46.

In another embodiment, where the general shape of the stove is in a hemispherical embodiment, air intake 42 could be in the bottom of the hemispherical outer shell 40. The inlet air would travel through the hemi-spherically-shaped air spaces 22, 24, and 26. In such embodiments, the fire bucket 20 could be any number of shapes. If the fire bucket 20 were a hemisphere then there would not be a distinction between the bottom 38 and the side 30 of the fire bucket 20. All that is necessary is that the air intakes 32 be placed so that the inlet air can travel along nearly the entire surface of the inner shell. Of course, in a hemispherical embodiment of the stove, it may be necessary to mount legs on the outside of the outer shell 60 to provide an air gap between the ground and the air intake 42.

FIGS. 5A through 5D show an intermediate shell 50 in a cylindrical form. Attached to the intermediate shell 50 are one or more tabs 56, one or more air intakes 52, and a bottom 58. Intermediate shell 50, the tabs 56, and the air intakes 52 may be created from a single piece of sheet metal as shown in FIG. 5D. The tabs 56 shown in FIG. 5D may be bent to create the tabs 56 shown in FIG. 5A. The gaps between the tabs 56 create the air intakes 52. Intermediate shell 50 may be secured to the rest of stove 10 by spot-welding, for example, the tabs 56 to the top lid 80. A bottom 58 is attached to the bottom of the intermediate shell 50.

However, there are any number of ways of connecting the intermediate shell 50 to the rest of the stove 10. For example, with the cylindrical embodiment, the tabs 56 could be mounted on the bottom 58 that is attached to the intermediate shell 50 and also mounted to the bottom 48 that is attached to the outer shell 40. Air intake 52 would then be created by the gap between intermediate shell 50 and top lid 80. This would reduce heat transfer between the top lid 80 and the intermediate shell 50. Another alternative is for the tabs 56 to be mounted to either inner shell 60 or outer shell 40. Depending upon the embodiment, there could be no tabs 56, one tab 56, or multiple tabs 56.

FIGS. 6A through 6D show a cylindrical embodiment of an inner shell 60. Attached to the inner shell 60 are one or more tabs 66, one or more air intakes 62, and a bottom 68. Inner shell 60, the one tabs 66, and the air intakes 62 may be created from a single piece of sheet metal as shown in FIG. 6D. The one tabs 66 shown in FIG. 6D may be bent to create the tabs 66 shown in FIG. 6A. The bottom 68 is attached to the bottom of the inner shell 60. Just as there are multiple embodiments of the tabs 56 there are multiple embodiments of the tabs 66. There could be no tabs 66, one tab 66, or multiple tabs 66. The tabs 66 shown could also be spot-welded to the top lid 80 of the stove 10. Additionally, the fire bucket 20 could be designed to rest directly upon the inner shell 60 rather than on the top lid 80.

FIGS. 7A through 7C illustrate an embodiment of a bottom 48. Bottom 48 is also representative of bottom 58 and bottom 68 with only a variation in diameter. Bottom 48 is a flat disk with a lip. There are alternative forms of bottom 48. For example, the ring embodiment previously mentioned. Also, in a collapsible embodiment of stove 10, bottom 48 could have guide rings for resting the cylindrical shells on it. Additionally, the bottom 48 could be removed and used as a lid on top of top lid 80 when the stove 10 is being transported and the fire bucket 20 has fuel in it. Also, instead of having a removable bottom 48, a separate lid similar to bottom 48 could be manufactured that was designed to fit over the top lid 80 for either storage or transport purposes.

FIGS. 8A through 8C illustrate an embodiment of a top lid 80 for a cylindrical embodiment of the stove 10. Top lid 80 is a flat ring with a lip on the outside edge. Extending above the top surface of the top lid 80 are cooking mounts 82. The top of the outer shell 40, the tabs 56, and the tabs 66 are attached to the bottom and/or lip of the top lid 80.

The cooking mounts 82 are also shown in FIG. 1. The cooking mounts 82 can be utilized, for example, for resting a frying pan or cooking pot on top of the stove 10. The cooking mounts 82 could also support, for example, a griddle, a dutch oven, or a grill on top of the stove 10. However, any type of cooking apparatus may be attached to the top of the stove 10. This can include a smoking unit, for example, for smoking foods. In that case, it may not be desirable to have tabs raised from the surface of the top lid 80 necessarily. Instead, it may be desirable to trap the smoke from the fire within the smoker apparatus. All that would be necessary is providing some means for the exhaust smoke from the solid fuel combustion to exit the fire bucket 20. Additionally, a collar could be provided to surround the exterior of the cooking mounts 82 to further trap heat at the bottom of a cooking surface or smoker. There are numerous embodiments of the top lid 80 and the cooking mounts 82.

Further embodiments of the top lid 80 could include, instead of mounts designed for holding a frying pan, mounts that could be designed for mounting wet gloves, shoes, or socks. Where an additional lid may be removably attached to the top lid 80 the one cooking mounts 82 could be substantially modified. For example, if the stove 10 was being utilized as fondue burner, it may be desirable to have a separate lid with a handle. The top lid 80 could be designed so that the additional lid can be rotated in and out of a locking position. Therefore the cooking mounts 82 would be a locking bracket. However, the need for a lid with a handle may be obviated somewhat because the stove 10 as a fondue heater would be cool to the touch and the entire fondue heater could be moved around easily.

It should be noted that both the top lid 80 and the bottom 48 may not independently exist depending on the geometric embodiment of the stove 10. For example, in a spherical embodiment, there essentially may not be a top or bottom attached to the outer shell 40, intermediate shell 50, or inner shell 60. Additionally, depending on the method of manufacture, such as roto-molding, even in the cylindrical embodiment there may not be a need for a separate bottom 48 or top lid 80.

Additionally, the tabs 56 and the tabs 66 could be welded in-line or in a star pattern to the bottom surface of the top lid 80. For example, it is likely, depending on the overall design, that the top surface of the top lid 80 will be hottest where the tabs 56 and the tabs 66 are welded to the top lid 80. Therefore, it may be desirable to have the tabs 56 and the tabs 66 welded in a row in line with the cooking mounts 82 shown in FIG. 8A so that the hottest portion of top lid 80 is the least accessible to be touched. For example, if a user is adding fuel to the fire bucket 20 while still leaving a cooking device resting on the cooking mounts 82 it would be more difficult for the user to touch the surface of the top lid 80 where the cooking mounts 82 are in the way. However, it may be desirable to distribute the heat across the surface of top lid 80 more evenly and so a different weld design for the tabs 56 and the tabs 66 may be used.

FIG. 2 illustrates that during operation inlet air enters through air intakes 42 and optionally through access 44 in the bottom of outer shell 40. FIG. 2 includes arrows that illustration the flow of air through the ductwork. The air travels upward through air space 22 created by outer shell 40 and intermediate shell 50. Inlet air flows through air intake 52 and downward into air space 24 created by the intermediate shell 50 and inner shell 60. The inlet air then flows through air intake 62 and into air space 26 created by inner shell 60 and fire bucket 20. The inlet air then flows upwards into the air intake 32 in the side 30 of fire bucket 20. The stove design allows inlet air to flow along nearly the entire length of the shells. Once combustion starts, combustion-induced convection pulls air through the air intake 32. This cools the exterior of the outer shell 40 as well as preheats the air for combustion within fuel space 28.

The air traveling through air space 22 cools the outer shell 40 and intermediate shell 50. The heat thereby being transferred to the air. As the air travels through air intake 52 the top lid 80 is cooled. The intermediate shell 50 and inner shell 60 are cooled as the air travels downward through air space 24. The air continues to get warmer. The now hot air travels through air intake 62 and mixes with the volatiles and other gases present in the air space 26. The mixed air now travels through the air intakes 32 and enters air space 28 of the fire bucket 20.

It will be appreciated that, although a three-walled ductwork is presently preferred as it provides a countercurrent heat exchange mechanism on the airflow therethrough, embodiments that only feature an outer shell 40 configured for insertion of a bucket into a lid thereon, and, thus, only a single air flow space may be used in certain embodiments. For example, where it is desirable to use less parts in order to reduce assembly time, a single jacket may be used with an insulative coating applied to the inside of the outer shell 40 and bottom 48.

The terms “upward” and “downward” are useful when describing the cylindrical embodiment of the stove, but may not apply when referring to other embodiments such as a hemispherical stove, where the inlet air movement would also have a horizontal component. Fuel space 28 of course can contain more than just fuel and can contain fuel, fire starting aids, air, ash, char, and/or anything else that relates to the combustion of solid fuels. Additionally, it is likely that combustion air would also reach the solid fuel through the opening 34 in fire bucket 20 as shown in FIG. 3C.

Any number of embodiments of the stove 10 may be utilized. In addition to the cylindrical, hemispherical, and spherical geometries previously mentioned, the stove 10 could be barrel-shaped, bucket-shaped, a trigonomal pyramidal, a square pyramidal, rectangular, a trigonomal prism, or a pentagonal prism, or any number of geometries. Essentially, there is no limit to the shapes that can be utilized with the stove 10.

Additionally, the stove 10 may be constructed so as to be assemblable on site. In a cuboid embodiment of the stove 10, each of the shells could be made from four panels that fit together and attach to the top lid 80. Thereby, allowing from compact transport of the stove 10. Even the cylindrical embodiment could constructed so that each shell is made of four quarters which can be taken apart and reassembled. Additionally, the stove 10 may be constructed from light-weight materials.

Additionally, just as the entire stove 10 may be of a variety of geometries, the fire bucket 20 may be of numerous geometries. It can be bucket-shaped as shown in FIGS. 3A through 3C. However, it could also be saddle-shaped, a hemispheroid, cuboid, or a cylindrical shape itself just to mention a few options.

In addition, the components of the stove 10 may be comprised of any number of materials, such as aluminum, glass, PYREX®, sheet metal, galvanized steel, stainless steel, porcelain, other ceramics, or any suitable polymer or any combination of those. The stove 10 can be manufactured in any number of ways. For example, the stove 10 could be made from sheet metal cut, rolled and welded together. Or the stove could be made from ceramics, blow molded as one unit and artistically hand-painted.

FIG. 2 illustrates the outer shell 40, the intermediate shell 50, and the inner shell 60 as fairly equally-spaced and uniform. However, air spaces 22 and 24 do not have to have the same width. Additionally, it is likely in an oval embodiment of the stove 10 that the width of the air spaces 22 and 24 would be wider in the middle and narrower near the top and bottom of the shells. The width of air spaces 22 and 24 is not critical, but if narrow widths are chosen, then it may be necessary to compensate for the reduced air insulation by elongating the shells, adding a fan, or by some other means.

The variety of designs possible for the stove 10 are really limited only by friction and heat transfer. If too narrow a gap is chosen and the length of the inner shell is made to long, then the inlet air convection created by the combustion may not be strong enough to actually draw the air from the air intake 42 of the outer shell 40 all the way through the air intakes 32 in the fire bucket 20. Therefore, one of the bounds on the design is not exceeding the suction force of the combustion of the solid fuel. However, there are numerous variables that can be adjusted to allow nearly any overall design to be workable. For example, a fan could be attached or the air intakes 42, 52, 62, or 32 could be made larger.

In one cylindrical embodiment of the stove 10, where the embodiment has a total height of about 1 ft. as measured from the bottom 48 to the top surface of top lid 80 and about a 10 in. diameter, the gap between the bottom 48 and the bottom 58 may be about 2 in. Similarly, the gap between the bottom 58 and the bottom 68 may be about 2 in. The gap between the bottom 68 and the bottom 38 may be about 2 to 2.5 in. Air space 22 and 24 may each be about 1 in. wide. Air intakes 42 may be holes of about 2 in. in diameter that are centered about 1.5 in. above the bottom of outer shell 40. Access 44, if the outer shell 40 were unrolled flat, may be a rectangle of suitable size to receive fan 49, for example, about 2.5 in. by about 7.5 in. may be used. If the intermediate shell 50 were unrolled flat, tabs 56 may measure about 2 in. long-by-1 in. wide. Tabs 56 may be bent at a 90 degree angle at about the 1 in. mark to create air intakes 52 that are about 1 in. tall by about 5 in. long. Air intakes 62 may be holes of about 1 in. diameter centered about 2 in. above the bottom of the inner shell 60. The cooking mounts 82 may rise about 1.5 in. above the top surface of the top lid 80. Cooking mounts 82 may be about 1 in. wide and about 1.5 in. long. The fire bucket 20 may be about 5 in. deep. The bottom 38 may have a diameter of about 4 in. The upper diameter may be about 6 in. Air intakes 32 may be in three rows. The centers of the air intakes 32 in the bottom row may be about 0.5 in. as measured vertically from the bottom of side 20. The middle row air intakes 32 may be about 1.5 in. from the bottom. The upper row air intakes 32 may be about 2.5 in. from the bottom. The air intakes 32 are in the bottom two-thirds of the side 30 and in the bottom 38 there are between nine and twelve air intakes 32. It will be appreciated that the cylindrical embodiment shown in the figures can be expanded or shrunk as needed, and that the relationship between these relative measurements may be maintained in such enlarged or reduced embodiments, or may be adjusted as needed to maintain proper airflow and combustion. In this embodiment, the stove 10 is most efficient when there is a two inch or more air gap between the layers.

The cylindrical presently preferred embodiment of the stove 10 is designed to be portable. However, stove 10 may also be embodied in permanent forms such as a patio heater. The stove 10 may be designed such that the entire device is disassemblable or it can be designed so that only the fire bucket 20 may be removed and the rest of the device is permanently attached together. Given the above description, it is clear that the stove 10 can be used in any number of situations; for example, it can be embodied as a camp stove, a survival stove, ice-fishing stove, -a fondue pot heater, an incense burner, inserted into a fireplace, a barbeque grill, a patio heater, or any combination of those uses in some multi-use apparatus. For example, the embodiments shown in FIGS. 1 through 8C could serve multiple uses. It could serve as a cooking unit and also as a heating unit.

Additionally, stove 10 could be used as a wall tent heater as the bottom and sides stay relatively cool, reducing the danger of igniting tent materials. Also, the stove 10 could be used as a document destroyer burner used by itself or in conjunction with a shredder to fully destroy documents to ash. One of the benefits of the stove 10 is that it tends to promote complete combustion of the solid fuels that are put into it. Therefore, there is less ash that remains after the combustion is completed. Also, as a result of the more complete combustion, less smoke is produced by the stove 10. Of course, if smoke is desirable, a damper could be adjusted to create more smoke.

The stove 10 may be used with any number of fuel sources; for example, wood, incense, wood pellets, charcoal briquettes, pine cones, grass, paper, clothing off of a survivor's back, coal, or essentially any solid combustible material or any combination of those materials. Obviously, different fuel sources will be easier to combust than others, but they all fall within the embodiments of the stove 10.

One of the benefits of the stove 10 is that the outer shell 40 will be at the most only warm to the touch during normal operation. However, it should be noted that if the stove 10 is operating in the sun it will be warmer to the touch than if operated in the shade.

The invention is not limited solely to stove-type applications. For example, the three-layer embodiment of the invention could be utilized in a hair dryer. The barrel of the hair dryer could be designed with the same pattern as shown in FIG. 2. The inlet air cooling the exterior of the barrel while the air travels into the heating chamber of the hair dryer. In this embodiment, the fire bucket 20 of FIG. 2 is recessed further within the inventive device. The fire bucket 20 instead of housing solid fuel contains a heating element and is the heating chamber of the hair dryer. The heated air travels along the inner surface of inner shell 60 and exits the inventive device just as smoke and heat exited the top of the stove embodiment.

Other embodiments of the inventive device include a new generation of pots and pans that are cool to the touch and for use on a gas range. Pots and pans could be designed so that the combustion air has to travel through a cooling ductwork before entering the burner and igniting the fuel. In this embodiment, the pan would still rest upon the burner grate just as a conventional pan does. However, attached to the sides of the pan is a ductwork similar to that shown in FIG. 2. The outside of the ductwork has holes near the bottom of the outside edge to allow air to enter the ductwork; however, the remainder of the bottom of the outside edge seals against the top of the range. The ductwork would not have a bottom such as that shown in FIG. 2 because of the necessity that the pan portion rest on the burner.

In this manner, the only way combustion at the gas burner can be sustained is by air reaching the fuel via the ductwork. The ductwork is cooled by the entering air. Because of the natural tendency for hot air to rise, the ductwork could be design to vent the exhaust gases at the top of the duct work. The exhaust gases could be directed along the exterior of the pan portion and ejected near the top perimeter of the pan. This would provide a pan that would not need a handle and would be cool to the touch. Additionally, when using a traditional pan on a gas stove much of the heat that is lost in the exhaust is never transferred to the pan. With the inventive device more of the heat stored in the exhaust gases can be transferred to the sides of the pan which may create somewhat of a dutch-oven effect.

Furthermore, electrically-heated sources could also be protected with the inventive device. For example, pots and pans designed for an electrically-heated range top could be designed with a mini-blower attached and with the cooling ductwork. That would eliminate the need for a handle on the pots and pans. The pots and pans could be picked up directly. An additional benefit with pots and pans with the inventive device is that heat is transferred along the side walls of the cooking surface, not just primarily towards the bottom of the cooking surface, therefore, creating somewhat of a dutch oven effect.

Additionally the inventive device can be utilized any time heat shielding is desired such as with mufflers, heat kilns, or smelting pots. The inventive device can be used as a heat sink housing for computers or other equipment that produce heat such hydraulically actuated equipment or boilers. The inventive device may be utilized anytime protection is desired between a heated source and a non-heated source.

It is apparent that the details of the apparatus and methods described herein can be varied considerably without departing from the concept and scope of the invention. The claims alone define the scope of the invention as conceived and described herein. 

1. A heating apparatus comprising: a combustion chamber with at least one air intake in the side of the chamber; a safety structure comprising: an inner shell; an intermediate shell; and an outer shell; wherein the combustion chamber and the safety structure are operably connected such that three parallel air spaces exist between the combustion chamber and the exterior of the outer shell; and wherein the combustion chamber and the safety structure are operably connected such that air can flow from an at least one air intake in the outer shell to the at least one air intake of the combustion chamber via the three air spaces.
 2. The heating apparatus of claim 1, wherein a gaseous- or vaporized-fuel burner is within the combustion chamber.
 3. The heating apparatus of claim 1, wherein the combustion chamber is configured for burning solid fuel.
 4. The heating apparatus of claim 3, wherein the combustion chamber is removable.
 5. The heating apparatus of claim 4, wherein a top of the combustion chamber is open to the atmosphere.
 6. The heating apparatus of claim 5, wherein the support structure is further comprised of a lid structure operably connected to the inner shell, the intermediate shell, and the outer shell.
 7. The heating apparatus of claim 6, wherein the combustion chamber rests directly upon the lid structure.
 8. The heating apparatus of claim 6, wherein attached to the lid structure is an at least one cooking support, wherein the at least one cooking support is configured to support a grill, a griddle, a pan, a dutch oven, a smoking chamber, or any combination thereof.
 9. The heating apparatus of claim 6, wherein the safety structure further comprises a damper.
 10. The heating apparatus of claim 6, wherein the inner shell, intermediate shell, and the outer shell are formed in geometric shapes selected from the group consisting of cylinders, barrels, conical frustums, hemispheroids, ovals, trigonal pyramidal, square pyramidal, cuboids, trigonal prisms, and pentagonal prisms.
 11. The heating apparatus of claim 5, wherein the combustion chamber is generally shaped as a conical frustum, a hemispheroid, a cylinder, or a saddle.
 12. The heating apparatus of claim 1, wherein the combustion chamber and the safety structure are formed from aluminum, glass, Pyrex®, sheet metal, galvanized steel, stainless steel, porcelain, ceramic, polymers, or any combinations thereof.
 13. The heating apparatus of claim 1, further comprising of an inlet air blower.
 14. The heating apparatus of claim 1, wherein the stove is portable.
 15. The heating apparatus of claim 7, wherein the safety structure is disassemblable.
 16. A portable stove comprising: a removable bucket including at least one port for air flow in a side thereof, and an insulative ductwork for providing airflow to the removable bucket through the at least one port.
 17. The portable stove of claim 16, wherein the insulative ductwork for providing airflow to the removable bucket through the at least one port comprises a ductwork having at least three concentric chambers.
 18. The portable stove of claim 17, wherein the insulative ductwork comprises the sides and bottom of the stove and are configured to remain relatively cool to the touch during continuous operation.
 19. A method of generating heat, the method comprising: combusting a solid fuel in a removable container; providing at least a portion of the combustion air to the removeable container through a side of the removable container, where the at least a portion of the combustion air is traveling through at least one pre-heating jacket encircling the removable container, prior to entering the container.
 20. The method of generating heat according to claim 19, wherein providing at least a portion of the combustion air to the removable container through a side of the removable container comprises providing the at least a portion of the combustion air through the bottom of the removable container. 